Pneumatic sheet material and method of making



NOV- 30, 1937. J. J. slNDLl-:R

PNEUMATIC SHEET MATERIAL AND METHOD OF MAKING Filed Oct. 23, 1933 other, but

mixture which Patented Nov. 30, 1937 UNITEDV 'STATES PNEUMATIC SHEET MATERIAL vAND METH- on oF MAKING I Jay J. sindler, Malden,

verse Rubber Compan Mass.,l assigner to Cony, Malden, M ass., a cor'- poration of Massachusetts Application October 23,

5 claims.

This invention relates to a pneumatic sheet material which is of general utility, but which finds especial application in the construction of shoes, and to a method of making the same.

The invention includes the concept of a sheet which may be made of substantially any thickness that may be desired. It is composed of a. plurality of hollow cylindrical tubes made ofresilient material, preferably rubber, and laid:to gether longitudinally and joined into an integral -sheet,` by direct Welding of the adjacent surfaces of the tubing. The resulting sheet is characterized by exibility, both Alongitudinally andtransversely, and also by a compressive pneumatic resiliency, resulting from the hollow tubular structure. This property may be emphasized by compressing and closing the ends of the tubes, so that the air cells are completely enclosed and thus acquire an increased resistance to high compression pressures and a capacity for distributing local applications of pressure lengthwise of the tube cavities. f

The structure of the integrated sheet may be regulated by the size, shape, composition and relative proportions of the individual tubes of which it is composed. Ordinarily the several lengths of tubing Will be of the same size and other characteristics generally, if not identical with each variations may be made therein and in their assembly in the sheet, according to practices and devices known to the .art of rubberl manufacture. The product or products obtained will vary accordingly and will be adaptable to various uses.

The method of the invention generally includes the preparation of a suitably plastic charge ofv material which may subsequently be solidied to a resilient body, such as a. vulcanizable rubber' may be made into hollow tubing in various ways, but preferably by extruding froml a die, in the form of a continuous strip. 'I'he tubtinuous tubing off in desired lengths and assembling them in such rows. It may also be effected by collecting the continuousA strip on a cylindri- The Thus, they may be welded together by slight presv contact.

integrated in various ways.

1933, serial No. 094,732 1 (ci. 15A- 2) sure when of plastic consistency, vent, or may be joined by a rubber solvent. The integrated sheet as thus formed is continuous and may be used in this condition or may be provided with a backing, as by laying a sheet of soft, un- Vulcanized rubber upon the aggregated layerv of without a soll tubing and compressing the two into intimate A backing sheet may be applied to both sides of the sheet of tubing, iff'desired. Rubber solvent may also be applied in this operation to join the tubing together and to the backing.

As thus assembled, the integrated layer 0r sheet of tubing or tubing and backing maybe subjected to vulcanization, whereupon comes more firmly integrated into is characteristically resilient and such may be incorporated in many constructions. If the construction is such that the whole may be later subjected to vulcanizatio ized sheet may be incorporated in such construction and subsequently vulcanized in the assembled product.

While the product as thus prepared is applicable for many purposes, a typical adaptation of the same is in the form of a sheet suitable to be incorporated in the construction of the soles for footwear of various types. A representatlveexample of the application and of one mode o1' carrying out the invention will in respect of a sheet materialsuitable fo poration in shoes, reference being had companying drawing in which:

Fig. 1 is a" diagrammatic view ofthe extrusion apparatus and mandrel;

Fig. 2 is a plan view of the joined together longitudinally;

Fig. 3 is a crossl single backing; A

a sheet which assembled tubings,

pliable and as' therefore be deLser'iloed the whole be- -section of the same "with ar double backing;

Fig. 5A is a cross-section of a single tubing showing a closed end; .Y Fig. 6 is a longitudinal cross-section cfa shoe in which the sheet material isfinorporated as an inner sole; f l

Fig. 7 is a longitudinal cross-section of a. shoe (with parts broken away) in which the sheet is incorporated'as the outer sole; and

Fig. 8 is a partial cross-section in the plane 8 8 0f Fig. 6.

Whilefthe rubber compositions which are' for may be rendered suitably plastic for the present invention are numerous and may be varied according to the Well-known principles ofthe rubber mixing and manufacturing art, a simple and satisfactory black composition may be prepared as follows: 1

. Parts Rubber 60.000 Carbon black 25.000 Palm oil 2.000 Zinc oxide 5.000 Sulphur 1.125 Stearic acid 1.000 Captax accelerator 1.000 Whiting 4.875

This composition, when thoroughly mixed, is

soft and plastic and readily acquires a uniform, tacky consistency. It is worked thoroughly, to exclude air bubbles if present, and placed in the chamber of the extrusion machine I. The spiral blades 2 are driven by any suitable source; of power (not s hown) and urge the mass forward into the conical shaped end 2 ofthe chamber,

where it is confined and forced around a die 3. This die is supported in the center of the conical end by a spider or framework 4, which is pref-A erably of thin cross-section, especially in the direction of flow of the plastic mass, and'may be adjusted and held firmly in position by set screws 5. One or more of the framework members may be made'hollow, as indicated at 6, to provide for the' entrance of air, which is sometimes utilized to introduce fine dust, such as talc, into thev inside ofthe tube, when it is desired to prevent the walls from adhering together.

The plastic composition, which heals together after passing the framework 4 into a continuous, uniform plastic mass, is extruded in the form of a continuous hollow tubing 8. The size and shape of the tubing is governed by the size and shape of the die 3 and of the nozzle 9-and the wall thickness and shape by the width of the annular aperture provided between them at the exit end.

'I'he continuous tubing, as it comes from the extrusion machine, may be cut olf in lengths and the lengths assembled. Itu may also be laid in f folded parallel lengths, as above indicated. 'As

` shown, however, it may conveniently be gathered' on a large cylindrical drum or mandrel Il in a gradual spiral, the coils being laid directly in close contact with each other, or slightly spaced apart and urged together by the operator or suitable cross-feeding deviceinot shown).

When the surface of the mandrel is thus covered with a layer of tubing, another mandrel may be mounted in its place, and the extrusion machine thus operated continuously, fresh charges of the rubber composition being added to the mixing chamber from time to time.

The cylindrical sheet of tubing as thus obtained may be further integrated simply by pressure, as by rolling it against a compression roll,

nally ofI the roll. This will tend to increase the length ofthe tubing and hence the diameter of therolled sheet. This has no serious eect but may serve to loosen the sheet from the mandrel. The sheet may then be cut longitudinally and stripped from the roll or may be slipped off the roll endwise, without cutting, if a/ cylindrical sheet is desired. To facilitate such removal, the surface of the roller or mandrel may be coated with an inert powder, soap or other lubricant.

As thus formed, the sheet has the appearance illustrated in Fig. 2.4 The successive lengths of prevented by blowing dust into the tube through the opening 6, as suggested above.

For some purposes, the integrated sheet as thus obtained may be regarded as a finished product, or to be completed by merely cutting to required shapes and sizes and then vulcanizing. Or the sheet, as thus made, may be combinedwith other materials and then vulcanized in association therewith.

In either mode of procedure, the successive lengths of tubing may be so chosen and assembled that they form a sheet of the desired sire and shape. The several lengths of tubing may also be made of varying diameters, and successive lengths may then be so chosen and assembled of the resulting sheet.

For other purposes, it will be desirable to combine the sheet with: a continuous backing sheet- In this event, the backing sheet is conveniently one of rubber or rubber coated fabric. It may, for example be of the same composition as the tubing and, likewise, unvulcanized. It may, however, be of an altogether different rubber composition, or may be of fabric, paper, etc., or the like.

If the backing sheet is of unvulcanized rubber, it may be applied to the tubing sheet, while on the mandrel, and firmly associated and integrated therewith by rubbing only or by compression.

The backing may be a single sheet or may be already composed of two or more layers of rubber, such as the layers I2, I3, in Fig. 4, in which, for example, ya llayer of crepe rubber I3 is associated with a. -layer of rubber I2 which is of the rsame composition as the tubing.

The' sheet of tubing, alone or associated with the backing sheet I2 (or sheets I2 and I3), may now be further integrated by subjecting to vul- I canization in the eustomaryvmanner, the proparched enect of the rounded tubing. At the same without permittirm the tubing to slip longituditime, each tube,4 owing to its fixed juxtaposition to the next (especially when the tubing sheet is attachedto a backing sheet) will resist extension and attening of the tubes. Thisl effect will be still further enhanced lengthwise of the tubes if the ends are closed and sealed, as above mentioned, so as to retain the enclosed 4air therein under pressure.

An integrated sheet thus produced may now be cut into various shapes to serve many purposes.

- Its use as an inner sole in footwear (rubber footwear in particular) will be described as a typical example. A canvas or duck upper I5 (Fig.- 6) is` first shaped and lasted to an inner sole IB in the be conilned to the heel and .ball portions where usual manner. 'Ihe upper I5 and the outer porthe greatest pressure oi' the .foot normally comes tion ofthe inner sole are cemented so that the and shocks and fatigue eifects are emphasized. foxing 2| may be placed around the lower por- To this end, the described sheet presents a pneu- 5 tion of the upper, thus serving the purposeA oi matic cushioning eii'ect, whether the ends of the 5 providing a bearing surface for subsequently tubingfare closed or not, and the necessity of securing the outer sole to the upper. wearing a rubber heel or a rubber outer sole is 'I'he integrated tubular sheet I1 may be a part removed; Accordingly, those who prefer shoes of or may comprise the inner sole I8, or it may with leather soles and heels` may be provided l be placed o'n separately as a filler, so-called. Alwith this type of shoe, and yet -retain the resil- 10 ternatively, it may be used in combination with lent cushioning for which rubber heels and soles or without any of the commonly used llers, are primarily worn. f k

viz.; rubber, rubbercoated fabric, fibrous mate- It is to be understood that the size, shape, rials, paper, etc. As shown in Fig. 6, it supplewall thickness and arrangement of the hollow I ments the separate inner sole I8 and receives tubing employed may be varied and selected at "15 5o tached all around the lower portionof the upper,

65 Other combinations will be readily evident to Wlth oa and is cemented," as well as the underside of the sizes, etc. of tubing may, for example. be inteinner sole' or any combination thereof. A foxing, grated into the sheet used in a given shoe,` to

toe cap, ete., if used, may be applied at this stage. vary these relative properties and although not 20 A iiller piece I9 is then set in place and the outer shown will be obvious from the drawing. sole 20 is attached to the assembly. A strip of Y In the vsecond type of assembly, above defoxihg 2| is then applied and, with Sufficient rollscribed and shown in Fig. 7, thetubing layer is ing and Dressing, to eiect firm contact and inteexposed and forms thel bottom of the shoe, givgration between the parts, the shoe, as shown in ing the tread surface a corrugated formation` 25 F18. 6, iS I'eedy for vulCahiZirlgwhich has an especially effective grip upon the Another arrangement of the pneumatic Sheet ground. It is also freely exible with iiexions of in a rubber shoe structure is illustrated in Fig. the foot, the successive Strips of tubing tending 7. 'I'he usual procedures for the construction of to open oui; accordingly, Even when the tubrubber shoes may be followed to the point where ing wells are worn through, the remaining upperv 30 the outer Sole is applied- It may. for example, portions are still attached to the sole and form comprise an uDDel' 22 and inner Sole 23 and tWO arched ribs, the lower edges of which present a. filler strips 24. As an outer sole, the integrated gripping tread to the ground and the upper p0rtubular Sheet 25 may be used, either ih the lmtions cushioning the foot as before, though not vulcanized condition, or in the vulcanized, or so eiectively of course as when the tubing sec- 35 Partially vulcanized State The tubular Outer tions are new and hermetically enclose the air' sole may or may not be backed, but in the instant in the an cells,I

Acase .the tubes 26 are provided with a backing Other uses for the pneumatic sheet materialv sheet 21 and crepe sheet 28. The ends of the tubes provided by this invention will occur to those 40 comprising the outer sole may be sealed, either skilled in the arts, when such properties are re- 40 by compressing before vuleahzihg, el' by means quired. For example, it may be employed as belt- -of a foxing or strips of rubber coated fabric 29, ing, when itis especially suitable to flex over puiplaced around the periphery of the outer sole. leys Without stretching or slipping, as carpeting To construct this type of Shoe. the upper 22 iS underlay, stair treads, lining, packing, upholsterlasted t0 One of the many Ordinarily used inner ing, sound, heat, or electrical insulation. etc. In 45 soles 23, which may be Waste fiber eeated fab* such applications, more than one layer of tubing ries, etc. A portion of the upper, to the line 32 maybe formed and integrated. It is to be underand the exposed side of the inner sole are cestood that various modifications as shown by line 32, and extends for a short dis- Well as ln the steps of the pro tance around the inner sole. Fillers 24 may or ture, but that such modl-oatl may not be attached. If so, they are well ce mented to outer sole to insure permanency. Then the tubular sheet or outer sole 25, preferably the folloWlng ololms- 55 backed by sheets of rubber, as shown, is added to I olalm:

the assembly, adhering rmly to the foxing all 1. A Shoo having an outery solo oomprlslng a around the Shoe, and to the bottom' (which has plurality of lengths of hollow rubber tubing disbeen Well cemented) by Toning and pressing posed in longitudinal continuous direct contact methods.. in common Practice in Shoe oonstruc' with each other and integrated throughout the 60 tion. t lines of contact'therebetween.

A third type of construction ls possible 1n that 2 A Shoe having an inner sole comprlsingva ,the Shoe may have both inner Sole and Outer S01@ plurality of lengths ofhollow rubber tubing dlsmade of the integrated tubular sheet (not shown). posed ln longitudinal continuous direct contaot ch other and integratedl throughout the those Skilled in the artl lines of contact therebetween.

In a shoe of such construction, the sole rls 3 A shoe havln yildable to pressure of the foot throughout its plurttllty of lengths of hollow rubber tublng dls area, but without tending to deform permanently and without decreased wear resistance. It is with each other, 70

easily made. light in weight. and in some types lines of contact with each other and with the of shoe may effectively replace the iller mateshoe' rialS Commonly employed between the outsole 4. Process of making iiexible sheet material, and the insole. As shown, the tubular sheet excomprising the steps of assembling a plurality 75 tends throughout the area of the Sole7 but it may of lengths of hollow, plastic, unvulcanized rubber 75 position and arrangement of the product, as 50 of lengths q: hollow, unvuicmimd nibber tubing. longitudinally in continuous direct contact with each other, immediately after forming the same and while the outer surfaces are in tacky condltion, to form 'a layer thereof, applying a backing sheet to said layer of tubes and integrating the same to each other and to said backing by vulcanimtion.

JAY J. SINDLER. 

